Back flow prevention system



Dec. 16, 1969 'r. J. SULLIVAN 3,483,884

BACK FLOW PREVENTION SYSTEM Filed Aug. 21, 1967 r m Hi; 48 42 lb Kw H1 m I 4? as so M 44 I F 7 4e 22 c l6 g I J IO as 8 T es 26 \Q I 76 2a 30 as I2 2 1 4o 1 1 as I w k INVENTOR 77mofl7ydsu/l/i/an BY M XL ATTORNEY 3,483,884 BACK FLOW PREVENTION SYSTEM Timothy J. Sullivan, Butte, Mont., assignor to Sullivan Valve and Engineering Company, Butte, Mont., a corporation of Montana Filed Aug. 21, 1967, Ser. No. 662,094 Int. Cl. F16k 31/12, 15/18; F16t 1/14 US. Cl. 137215 6 Claims ABSTRACT OF THE DISCLOSURE the invention, drain valve means are provided having an 2.

inlet connected between the two check valve means, said drain valve means being automatically opened upon closure of said diaphragm operated main valve means.

Many types of back-flow valves and back-flow valve systems have been proposed in the patented prior art. Pressure-responsive main valves have been proposed that are designed for automatic closure upon the detection of back flow pressure surges at a given downstream location. Backflow valves of the check valve type have also been proposed for preventing reverse pressure surges from reaching the supply conduit. Many systems combining various types of valves have also been proposed for providing a safe protective system.

The known systems possess the inherent drawback that the backflow valve means often leak after extended periods of use, and when the components become dirty or corroded, do not seal with adequate rapidity or with a sufiiciently tight fluid seal.

The primary object of the present invention is to provide a back flow prevention system including pressure-responsive diaphragm operated main valve means connected in series with a pair of check valve means, whereby triple back flow protection is afforded. In accordance with an important further feature of the invention, a fourth protection is afforded by connecting a drain valve between said pair of check valves, said drain valve being normally closed and being automatically opened upon closure of said pressure responsive main valve means.

In accordance with a more specific object of the invention, the first one of the pair of check valves is slidably mounted on a valve stem carried by the diaphragm means that operate the main valve means. The said first check valve means and the main valve means are arranged for seating engagement with opposite sides of a single valve seat.

A more specific object of the invention is to provide normally closed drain valve means connected between the two check valve means and automatically operable to the open position by closure of the pressure-responsive main valve means. The drain valve means is operated by a centrally pivoted member that is spring-biased in a direction etfecting closure of the drain valve means.

Other objects and advantages of the invention will become apparent from a study of the following specification when considered in conjunction with the accompanying single figure of drawing, which is a sectional view of the preferred embodiment of the back flow prevention system of the present invention.

As shown in the drawing, the backflow prevention system includes a main valve body 2 having an inlet 4, a

nited States Patent 3,483,884 Patented Dec. 16, 1969 "ice first outlet 6, a transverse wall 7 that contains a main valve seat 8 and defines an inlet chamber 10 and an outlet chamber 12, a drain outlet 14 in communication with said outlet chamber. The outlet 6 is connected by conduit 18 with the inlet 20 of a second valve body 22, said body having a second outlet 24, and second valve seat means 26 defining second inlet and outlet chambers 28 and 30, respectively.

Secured to the main body 2 is a drain valve body 34 having an inlet 36 in communication with the drain outlet 14, a drain outlet 38, and a drain valve chamber 40. Also secured to the body 2 is a diaphragm housing 42 containing a diaphragm 44 defining a lower chamber 46 in communication with the main valve inlet chamber 10 via the housing opening 47 and diaphragm outlet 16, and an upper chamber 48 in constant communication with the outlet chamber 30 of the second valve body 22 via conduit 50.

The diaphragm 44 carries a diaphragm plate assemblage 54 including a main stem 56 that extends downwardly through a stationary guide sleeve '58 carried by spider 69 secured in diaphragm housing opening 47. Slidably mounted on the stem 56 is a main valve body 62 that is biased downwardly (together with diaphragm 44, plate assembly 54 and stem 56) by spring 64 toward a closed position on valve seat 8. Stop 66 secured to main stem 56 serves to lift the main valve 62 from seat 8 upon upward movement of diaphragm 44 as will be described below. Also slidably mounted upon the stem 56 is a first check valve 68 that is arranged in the outlet chamber 12 and is biased upwardly toward a closed position upon seat 8 by a spring 70' that is supported at its lower end by a spider 72 secured in inlet opening 36 of the drain valve body 34. Packing gland caps 74, 76 biased by the springs 64 and 70, respectively, serve to take up-in a threadless manner-any wear that occurs in the valve packing.

The lower end of the main valve stem 56 extends downwardly through the spider 72 and is adapted at its lower extremity to engage one end of the drain valve lever 80 the central part of which is pivotally connected with drain valve body 34 by a pivot 82. At its other end, the lever 80 carries a drain valve 84. Spring 86 having tension adjusted bolt means 88 normally biases lever 80 in the clockwise direction about pivot 82 to seat valve 84 upon its valve seat to close the drain outlet 38. The arrangement is such that when diaphragm 44 is in the illustrated lowermost position closing main valve 62 on its seat 8, the lower end of stem 56 engages lever 80 to pivot the same in the counterclockwise direction against the force of spring 86, whereby drain valve 84 is raised to its illustrated open position. The drain valve body includes a removable plug 87 for the connection of vacuum breaker means, if desired.

Mounted in the outlet chamber of the second valve 22 is a check valve 89 that pivots about pivot shaft 90 and is biased by spring 92 in the clockwise direction toward a closed position relative to its seat 26.

OPERATION Upon the supply of pressure fluid to the inlet chamber 10 of the main valve body 2 and to the lower diaphragm chamber 46, the diaphragm 44 and stem 56 are raised to open valve member 62 from its seat 8. The drain valve 84 is now closed upon its seat owing to the clockwise pivotal movement of lever 80 by spring 86. The pressure fluid then opens the first check valve 68 against the restoring force of spring 70, whereupon fluid is supplied to drain chamber 40 via chamber '12 and openings 14 and 36, and to inlet chamber 28 via chamber 12 and conduit 18. When the pressure in chamber 28 exceeds a given value, check valve 89 is pivotally opened against the restoring force of spring 92, whereupon pressure fluid is supplied to outlet 24 via chamber 30 and to the upper diaphragm chamber 48 via chamber 30 and conduit 50. The diaphragm 44 asumes an equilibrium position in which the pressure differential between diaphragm chambers 46 and 48 maintains main valve 62 in an open position.

Assume now that a back flow pressure increase is supplied to the outlet chamber 30 of the second valve in the reverse direction via outlet conduit 24a. Check valve 89 is closed upon seat 26 by spring 92, and the pressure increase is transmitted to the upper diaphragm chamber 48 via conduit 50. Diaphragm 44 now m ves downwardly to permit closure of the main valve 62 upon the seat 8 by spring 64, and opening of drain valve 84 as a consequence of the counterclockwise movement of lever 80 against the force of spring 86 by stem 56. Owing to the closure of main valve 62, check valve 68 is closed on the seat 8 by spring 70. It is apparent that even it check valve 22 should have a slight leak, back flow fluid will be positively prevented from returning to the supply line 4a, owing to the opening of chamber 28 to drain via open valve 84, and to the closing of check valve 68 upon its seat 8.

vhen the back flow pressure diminishes to the point that the pressure diflerential between diaphragm chambers 46 and 48 returns to its initial balanced condition, diaphragm 44 and stem 56 are raised to open main valve 62 and to permit closure of drain valve 84 by spring 86. Check valves 68 and 89 are then opened by the pressure fluid, which fluid is then transmitted to the outlet conduit 24a.

It is apparent that triple backflow protection is afforded by the provision of the two check valves in combination with the pressure-responsive diaphragm-operated main valve, and that a fourth protection is provided by the drain valve means that are automaticall opened up n closure of the main valve means.

While in accordance with the patent statutes the preferred form and embodiment of the invention has been illustrated and described, it will be apparent that to those skilled in the art various changes and modifications may be made in the apparatus described without deviating from the invention set forth.

What is claimed is:

1. Back flow prevention apparatus, comprising main valve means (2) having an inlet (4), an outlet (6), and a normally-closed main valve member (62) normally interrupting communication between said inlet and outlet;

normally closed first (68) and second (89) one-way h check valve means connected successively in series with the outlet of said main valve means for conducting fluid from the inlet of said main valve means to the outlet of said second check valve means; drain valve means (84) having an inlet connected between said first and second check valve means, said drain valve means including also a drain outlet (38),

4 and a drain valve member (84) normally closing said drain outlet;

pressure-responsive means including a single diaphragm (44) operable in response to the pressure diflerential between the inlet pressure of said main valve means and the outlet pressure of said second check valve means;

first operating means (66) responsive to movement of said diaphragm in one direction for opening said main valve means;

and second operating means (80) responsive to movement of said diaphragm in the opposite direction for opening said drain valve means.

2. Apparatus as defined in claim 1, wherein said first operating means includes a main stem (56) carried by said diaphragm, said main valve member being slidablv mounted on said stem.

3. Apparatus as defined in claim 2 wherein said second check valve means comprises a pivotally mounted valve member, and spring means biasing said valve member toward a closed position.

4. Apparatus as defined in claim 2 wherein said main valve means includes a valve seat, and wherein said main valve member is adapted for seating engagement with the inlet side of said seat;

and further wherein said first check valve means includes a first check valve member arranged for seating engagement with the outlet side of said valve seat.

5. Apparatus as defined in claim 4, wherein said main stem passes through said valve seat, and wherein said first check valve member is slidably mounted on said main stem; and further including spring means biasing said first check valve member toward a closed position relative to said seat.

6. Apparatus as defined in claim 5, wherein said means for opening said drain valve member c mprises a pivotally mounted lever arranged for operation by said valve stem to open said drain valve member when said main valve member is in the closed position.

References Cited UNITED STATES PATENTS 686,409 11/1901 Locke 137496 K 1,850,063 3/1932 Pepper 137614.2 1,960,144 5/1934 Entriken 137218 2,620,816 12/1952 Griswold 137-2l8 3,016,914 1/1962 Keithahn l37527 X FOREIGN PATENTS 586,166 3/ 1947 Great Britain.

ROBERT G. NILSON, Primary Examiner US. Cl. X.R. 

